Synthesis of hexagonal SiGe semiconductor using high pressure and temperature

Hexagonal SiGe semiconductor for optoelectronics: synthesis of the material succeeds using high pressure and temperature opening a possible solution to a pressing optoelectronic problem.


Hexagonal SiGe semiconductors are a promising material for optoelectronics - for seamlessly combining electron and photon technology. Under extremely high pressure and temperatures above 1,500 degrees Celsius, a team led by George Serghiou from the University of Edinburgh in Scotland and Hans J. Reichmann from the German Research Centre for Geosciences Potsdam (GFZ) succeeded in synthesising the material. To do this, they used laser-heated diamond stamp cells and multi-anvil presses, among other things, as are commonly used for geoscientific experiments. The publication ‘Chemistry - A European Journal’ was chosen as the cover story.

The challenge of optoelectronics: Materials for the connection of light and electricity

Electrons and photons, i.e. current and light, are the information carriers of today's IT systems. A central challenge in optoelectronics has long been to develop seamless communication between current and light conducting systems. A material must fulfil two decisive criteria so that such a seamless transition between electron and photon technologies can be achieved in components: The material should have a direct band gap in its electronic structure so that the conversion of light into current and vice versa takes place as efficiently as possible. And it should be chemically compatible with silicon, because semiconducting silicon with a cubic diamond lattice structure is still the most important basic material in the electronics and information industries. However, silicon itself does not have a direct but an indirect band gap in its electronic structure, which makes the conversion of electricity into light very inefficient. 

Promising approach: combine silicon and germanium in a hexagonal structure

For the development of semiconductors with a tailor-made direct band gap, different materials are combined with each other, among other things. Recent work shows the importance that hexagonal silicon-germanium (SiGe) semiconductors, for example, can have for combining electronics and photonics. Specifically, a study by Fadaly et al. (2020) fabricated 0.0005 millimetre thick nanowires of SiGe with a hexagonal symmetry that exhibit direct bandgaps. They were fabricated on a matrix of gallium arsenide (GaAs) nanowire cores. In the study, however, the researchers emphasise that it is necessary to fabricate matrix-free hexagonally crystallised SiGe. This SiGe should also be larger.

SiGe synthesis using high pressures and temperatures

This is exactly what the international research group led by George Serghiou from the University of Edinburgh in Scotland and Hans J. Reichmann from the German Research Centre for Geosciences Potsdam (GFZ) has been working on in recent years.  In a study published in the journal Chemistry A European Journal, they show how they succeeded in developing hexagonal, binary SiGe semiconductors.

Essential prerequisites for this were synthesis and characterisation methods under high pressures of 12 to 17 Giga-Pascal (120 to 170 Kbar) and temperatures above 1500 degrees Celsius (~1800 K). The material was produced in laser-heated diamond anvil cells and in multi-anvil presses as also used in experiments investigating planetary interiors. The crystalline and the chemical composition of the resulting materials can be investigated with state-of–the-art characterization methods including synchrotron-based angle dispersive X-ray diffraction, precession electron diffraction and electron microscopy.

Successful approach for the targeted manipulation of optoelectronic properties

The research team thus succeeded in synthesising new, matrix-free SiGe materials with a hexagonal lattice that are about 1 millimetre in size. The samples show different types of hexagonal SiGe crystals with different stacking orders of the crystal planes. This is also significant because the band gap can be possibly manipulated not only as a function of the chemical composition of the material, but also as a function of this stacking sequence. This could possibly be a new approach to tailor the optoelectronic properties of this material system according to the specific application needs.

Original publication: Hexagonal Si-Ge Class of Semiconducting Alloys Prepared Using Pressure and Temperature.
George Serghiou, Nicholas Odling, Hans Josef Reichmann, Gang Ji, Monika Koch-Müller, Daniel J. Frost, Jonathan P. Wright, Reinhard Boehler and Wolfgang Morgenroth Chem. Eur. J. (2021); DOI: 10.1002/chem.202102595

Scientific contact

Scientific contact

Additional News

German map with quality-checked data points, shown as columns

A new heat-flow analysis shows higher values for Germany

P. Martinez-Garzon in a forest next to a giant split rock

Dr. Patricia Martinez-Garzon wins ERC Starting Grant for her project QUAKE-HUNTER

Map of Türkiye with the marked epicentre of the earthquake in the northwestern part of the country

Background on today's earthquake in northwest Türkiye

Topography map of the alps.

What is driving the Alps upwards?

Groupp picture ICDP/IODP Kolloquiums

Joint IODP/ICDP-Colloquium at GFZ

Teachers in lecture hall during lecture

"Extreme Events in the Earth System" - 20th "System Earth" Autumn School

Two young researchers stand in front of trees holding their certificates, next to them stands Ludwig Stroink, who awarded the certificates.

“GFZ Friends” honours Theresa Hennig and Lei Wang with the “Friedrich-Robert-Helmert Prize…

Satellite image of a desert area: Colorful spots show different minerals.

German environmental satellite EnMAP: start into regular operation

On the left, a measuring tower in a low overgrown tundra landscape.

More methane from Siberia in summer

[Translate to English:] Profilfoto mit schwarzem Rahmen von Henning Francke

Obituary: Henning Francke

Group photo with projekt responsible

Making geodata interoperable and suited for curiosity driven research: GEO-INQUIRE project…

Schema Energiebereitstellung durch Geothermie

European Geothermal Congress from 17 to 21 October 2022 in Berlin

Gruppenfoto PAM

International Conference on Polar and Alpine Microbiology

Leni Scheck Wenderoth

“AWG Professional Excellence Award” for Magdalena Scheck-Wenderoth

Ausbildung am GFZ

Berufsausbildung und duales Studium am GFZ

Dr. Ute Weckmann during the opening speech of the workshop

Dr. Ute Weckmann takes over the chairmanship of IAGA Division VI

Anke Neumann aon a boat during a research trip

Dr Anke Neumann is a Senior Humboldt Research Fellow

Earth Model

New DFG priority programme on deep Earth evolution over geologic time

Logo of the Helmholtz Innovation Labs: written words only

Successful interim evaluation of the two Helmholtz Innovation Labs at the GFZ

Schematic of plunging Earth plates under the ocean with water transport and the Al molecules involved: This is how water migrates deeper into the Earth than previously assumed.

Water is seeping deeper into Earth than expected

From the air, a view of Istanbul, a city of millions, and the surrounding sea.

"Earthquakes don’t occur out of nowhere"

Group photo with all the people who attended the farewell

Honouring Prof. Onno Oncken with a scientific colloquium

DEUQUA Logo mit Mammut und Friedenstaube

DEUQUA 2022 Tagung am GFZ

PAW Logo

Postdoc Appreciation Week Germany

Building, photo taken in winter, Isaac Newton Institute

Simons Scholarship for Dr Monika Korte

Die Verteilung der seismischen Stationen auf einer Karte der Region.

How deeply does Eifel volcanism sleep?

Geomagnetic Field. Space with stars, Earth with animation around

GFZ film among the finalists of the Earth Futures Festival 2022

Earth's radiation belt: High-energy particles modelled around the Earth. The particles are ring-shaped

A new population of particles in the Earth’s radiation belts

[Translate to English:] Die teilnehmenden GFZ Mitarbeiter als Gruppenfoto

2nd proWissen run in Potsdam with successful participation by GFZ employees

The group on the first day of work.

New faces at the GFZ - start of the training year 2022/2023

back to top of main content